Can the mother of my child disappear with my child without notifying me or seeking my consent to move?

Are you on the child's birth certificate? If not you are not legally the father. If you are, is there a support order in place; a visitation order? If not there is no requirement she tell you anything. If there is a visitation order in place, when you are not given you visitation you can seek relief from a court to enforce the order. If there is no order in place, you need to get one. Then you will known where your child is.

What you need to do is file a petition for determination of paternity, custody and child support. Right now, both of you have the right to custody. When you get a court order in place and she does something like this, you can get the police involved and she can be held in contempt of court. Call the Idaho Bar Association and get a referral. This may not be an easy process.